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Low millisecond resolution in performance profiler and performance.now()
Reported by
gebacken...@gmail.com,
Dec 21 2017
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Issue descriptionUserAgent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/63.0.3239.108 Safari/537.36 Steps to reproduce the problem: 1. Open a WebGL demo, e.g. http://madebyevan.com/webgl-water/ 2. Open the performance profiler and start a record for a few seconds What is the expected behavior? Frame by frame execution times with precision down to a 100th millisecond. What went wrong? - Execution timings with only millisecond precision. - Many execution paths that were captured before aren't captured anymore. The profiler misses many things. - Some functions are reported to take 1 or 2ms but I'm under the impression that this may be off by at least 50%, as if timings are simply rounded. Did this work before? Yes unkown Chrome version: 63.0.3239.108 Channel: stable OS Version: 10.0 Flash Version: I'm experiencing this on a new PC with this setup: OS: Windows 10 CPU: AMD Ryzen 1600 Browser: Version 63.0.3239.108 Until recently it worked with another System with windows 10, I can check it's chrome version as soon as I have access to it again.
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Dec 21 2017
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Dec 22 2017
Tried testing the issue on Win-10 using chrome reported version #63.0.3239.108 and latest canary #65.0.3300.0. Attached a screen cast for reference. Following are the steps followed to reproduce the issue. ------------ 1. Open a WebGL demo, e.g. http://madebyevan.com/webgl-water/ 2. Open the performance profiler and start a record for a few seconds 3. Observed that Animation frame fired took more than 10 millisecond. gebackene.ente@ - Could you please check the screen cast and please let us know if anything missed from our side. This will help us in further triaging of the issue. If possible please provide a screen cast for better understanding of issue. Thanks...!!
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Dec 22 2017
Reporter, make sure "High resolution CPU profiling" is enabled in devtools options. By default 1ms precision is used, while this option enables 0.1ms precision [1]. You can also try enabling an experimental tracing-based profiling: 1. open and enable chrome://flags/#enable-devtools-experiments 2. restart the browser and open devtools options 3. click "Experiments" 4. press "Shift" key 6 times (ignore and close any OS dialogs) 5. enable "Timeline: tracing based JS profiler" [1]: https://cs.chromium.org/chromium/src/third_party/WebKit/Source/devtools/front_end/timeline/TimelineController.js?l=174&rcl=2ff0a9383fb2be7c694408a6e30cf5b3aade8292
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Dec 22 2017
krajshree: Your screencast looks exactly like how I'm doing it. I've attached a screencast from my own results, including the results of performance.now() woxxom: "High resolution CPU profiling" is enabled. Same results with "Timeline: tracing based JS profiler" enabled.
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Dec 22 2017
Thank you for providing more feedback. Adding requester "krajshree@chromium.org" to the cc list and removing "Needs-Feedback" label. For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot
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Dec 22 2017
I just checked it on my office PC where everything works as expected. Same OS (Windows 10), same Browser version (63.0.3239.108), just a different CPU (Intel i7-3770K). Performance profiler and performance.now() have sub-ms resolution on this system. So it's only my work@home that suffers from ms resolution.
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Dec 26 2017
Unable to reproduce the issue on Win-10 using chrome reported version #63.0.3239.108 and latest canary #65.0.3303.0. Attached a screen shot for reference. Could anyone from Platform>DevTools team please have a look into the issue as it is not reproducible from TE-end. Hence, removing the Needs-Bisect label. Please feel free to add the same if required. Thanks...!!
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Dec 28 2017
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Feb 21 2018
I have the same issue on the virtual machine with low performance. Chrome version: 66.0.3347.0 , dev (puppeteer) OS: Windows 10.0 (virtualized) CPU: Intel Xeon E5-2690 Turning on the "Timeline: tracing based JS profiler" option has no effect. By the way, the "Idle" timing in the profiler is rounded to 0.1 ms. Is there any way to workaround the rounding of performance.now() at least up to 0.1 ms? (flag, other method, etc.)
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Feb 21 2018
It looks like you don't have "High resolution profiling" option turned on. Can you please confirm? Please do no use tracing based JS profiler experiment. It'll likely break things.
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Feb 22 2018
"High resolution profiling" option is turned on.
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Feb 22 2018
I deployed the image of this OS (Hyper-V) on the local machine, where Chromium works correctly. There is the same problem - the timings are rounded to 1ms.
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Feb 22 2018
Update from my side: I'm also still experiencing this issue on chrome 64.0.3282.167, as well as canary 66.0.3352.0.
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Dec 17
Works just fine as of M-71. If the resolution is 1ms then the "High res profiling" option is likely turned off in the DevTools settings. Closing it as not reproducible.
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Dec 20
I have 0.1ms precision for performance.now() in chrome 71 now, which is better. The "High res profiling" option still doesn't change anything though. |
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Comment 1 by gebacken...@gmail.com
, Dec 21 2017